Recently, PM 2.5 existing in the atmosphere, which is floating particulate matter having a diameter less than 2.5 μm, is of a large environmental concern. For this reason, an apparatus for analyzing a concentration of PM 2.5 in the atmosphere and elements included in PM 2.5 has been developed in order to monitor a status of PM 2.5. It is considered that the source of PM 2.5 can be predicted by analyzing elements included in PM 2.5. For example, JP 2008-261712A discloses a measurement apparatus for automatically and continuously analyzing kinds of elements that form floating particulate matter in the atmosphere by using a fluorescence X-ray generated from the particulate matter.
An analyzing apparatus, such as the above-described measurement apparatus, for analyzing compositions of elements using a fluorescent X-ray, includes an X-ray source that generates a primary X-ray, which is emitted to an object to be measured in order to generate the fluorescent X-ray, and a detector that detects the fluorescent X-ray. The X-ray source and the detector change their properties as time elapses. Therefore, in the above-described measurement apparatus, in order to reduce influences on a result of the analysis caused by such a time-dependent change, a calibration of an intensity of an X-ray is performed every time when performing the composition analysis, using a standard specimen such as a specimen for performing a span calibration. As described above, if the calibration of the intensity of the X-ray is performed every time when performing the composition analysis, the influences caused by the time-dependent change (a time degradation, etc.) can be eliminated every time when the calibration is performed.
On the other hand, if the composition analysis of collected particulate matter such as PM 2.5 is continuously performed in the atmosphere, the time-consuming calibration using a standard specimen, etc., cannot be performed. Therefore, if the conventional calibration method of the intensity of the X-ray is used when the analyzing apparatus continuously performs the composition analysis, the composition analysis is influenced by the time-dependent change of the analyzing apparatus.